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Why is this study being conducted?

North Carolina has been identified by the National Oceanic and Atmospheric Administration (NOAA) as one of three states with significant vulnerability to sea-level rise. The state possesses the second largest estuarine system on the U.S. Atlantic coast, with an extensive barrier island chain vulnerable to overwash and breaching along several reaches. This study serves to examine the potential impact to the living and built systems that underpin and sustain the economy and way of life for North Carolina citizens.  This study addresses three gaps in the current state of knowledge:

  • Lack of statewide, quantified assessment of future flood losses if there is an increase in sea level elevations.
  • No efficient methodology exists for utilizing best available methodology, modeling, and to calculate and track impacts if sea levels increase.
  • No efficient methodology for assessing the cost effectiveness of loss avoidance strategies.

Who oversees the study?

SLRIS is being conducted out of the NC Division of Emergency Management, Office of Geospatial and Technology Management. The study also has an advisory committee comprised of over 30 members from State and Federal agencies, academia, stakeholder organizations, and other public and private sector experts.

What is the scope of this study?

The primary focus of this study is to provide a robust analysis of the potential changes to coastal flood hazards and impacts due to future sea-level rise and storminess in North Carolina. The SLRIS adopted a scenario-based approach to evaluate potential sea level rise, storminess, land development, and resultant flooding. System-wide impact assessments are performed for permanent flooding resulting from sea level rise, temporary flooding due to 1% annual chance surge events, annualized damages, and adjusted historical events. Hazards are overlaid on the built environment to assess impacts for projected future conditions at 2025, 2050, 2075, and 2100.

This study will develop cost effective consequence reduction strategies based on the identified impacts. The strategies will consider economic impacts, regulatory and implementation cost, stakeholder acceptance, and potential cost savings, and be evaluated based on how well they perform across a range of potential future conditions. Study results will be provided in a report and interactive internet portal.

What are the sea level rise scenarios and the basis for the scenarios chosen for this study?

SLRIS will assess and report change in flood hazards for sea level rise scenarios from 0 to 0.4 m by 2100 at increments of 0.1 m. These scenarios represent a range of projections based on historical observations of sea level rise within the state of North Carolina.  

Is the study considering climate change factors other than sea level rise?

Yes, SLRIS also considers potential changes to tropical storm frequency and intensity, referred to as  “storminess.” Storminess scenarios are founded on future projections of tropical storm occurance by category in the Atlantic Basin. These projections are then related to the North Carolina coast by historical landfall probabilities within the state. These changes are then input into the storm surge and flood probability modeling framework to determine the potential change in future flood elevations.

What are the study products?

The SLRIS study products will include a report and interactive sea level rise web portal. The study report will provide detailed documentation of the study procedures and assumptions, with results reported by scenario and receptor. The results will contain maps with jurisdiction, county, and state level summaries in tabular and cartographic formats. Products will include identification of impact hotspots, state level strategies, and cost effectiveness evaluation. The study web portal is an interactive display of report results in geospatial and tabular formats, with impacts displayed by sector. Because the study framework is designed to provide for assessments up to 1.0 m, additional information will be made available for state and county officials through the Office of Geospatial and Technology Management’s Integrated Hazard and Risk Management study viewer.

What is not being produced from SLRIS?

The study will not prove or disprove any sea level rise projections or causations, nor will the study assign probabilities or likelihoods for a given sea level rise scenario. Products of the study will not be incorporated into FEMA Flood Insurance Rate Maps. Potential impacts at site-specific locations will not be reported. Further, the study will not endorse or recommend any of the flood impact management studies produced.

Who is the study audience?

The primary study audience SLRIS is directed towards is federal and state government policy makers, including the U.S. Congress, North Carolina General Assembly, Governor’s office, FEMA and the NFIP, and other coastal states. A secondary study audience includes coastal counties and municipalities, NC state departments with regulatory authority, the US Department of Defense (e.g. military bases in North Carolina coastal areas), DHS-NIPP, and Federal Agencies with regulatory authority (i.e., NOAA, EPA, USACE). The results of this study will be prepared such that the audience will be able to comprehend and acknowledge the impacts associated with future sea level rise and storminess due to climate change.

How is the study assessing future flood impact management options?

Strategies are being developed at the state level by receptor for broad scale application. A key goal of the process is to define how systems can accommodate sea level rise at minimum disruption or cost, based on consequences identified by the study. Strategies will be evaluated for performance across a range of potential future conditions and against “no action” alternatives and consider impacts, costs, acceptance, and return on investment. These strategies provide a starting point for awareness and planning, and are not direct policy or regulation outputs.

What are the implications from the study?

The study is being conducted by the Office of Geospatial and Technology Management, which is not a regulatory agency. As such, the study has no direct regulatory or insurance implications. Flood prevention ordinances and policy are set by the land use authorities.  The North Carolina Floodplain Mapping Program does not plan to incorporate products of this study into Flood Insurance Rate Maps.  The National Flood Insurance Program regulations exclude future conditions in the development of Flood Insurance Rate Maps. Flood insurance rates under the NFIP are set by FEMA at the national level, thus, results from this study will not affect rate levels.